Projectile.



W. K. RICHARDSON.

. Patented June 1, 1915. 1,141,415.

radius, thereby reducing the velocity of WILLIAM RICHARDSON, 0F;LEAVENWOBTH, KANSAS.

Pnomc'n'LE.

Specification of Letters Patent.

Patented June 1, 1915.

Application filed March 20, 1915. Serial No. 16,773.

To all whom it may concern:

Be it known that I, WILLIAM KING Rrcn- Annson, citizen of the UnitedStates, residing at Leavenworth, in the county of Leavenworth and Stateof Kansas, have invented certain new and useful Improvements inProjectiles, of which the following is a specification.

The object of this invention is to produce a long range armor-piercingprojectile that may be used in present constructed guns. This object isattained by reducing the atmosphere resistance to the projectile, 1st,by employing a sharp pointed cap, the ogive of saidacap being struck onat least a 7 caliber displacement of the air, and a consequentconservation of power; 2nd, reducing the cyl inder length of theprojectile so that length will but slightly exceed the caliber of thegun for three purposes: 1st, to reduce the skin friction which isdirectly as the surface; 2nd, to conserve'the rotary velocity that isimpressed upon the projectile by the rifling of the gun in its motion oftranslation; 3rd, conserving some of the energy of the compressed airenveloping the projectile at its highest velocity -flight,'which isinversely as the caliber of the shfot. As an illustration, the presentservice rifle bullet, 150 grains, .3" caliber 2,730 velocity ft.seconds, conserves most of the pressure energy that is available to asquare base, due to the fact that the bullet travels but a fraction ofan inch before the compressed air enveloping the bullet rexpands at thebase of the bullet, and before that pressure is dissipated, due to itsvelocity of expanslon. e

The 3rd object of this invention is attained' by employing "a taperedrear end terminating. in a reduced base at right angles to thelongitudinal axis of the projectile. Most of the loss in kinetic energyof a projectile in flight at long range heretofore has been due to theconstruction of the. base or rear-end, which have generally equaled inarea to the cross-sectional area of the cylinder of the projectile.

There are many important factors to be taken into consideration in theconstruction of a base or rear end of a projectile in order to utilizethe pressure energy of the atmos-' phere. As many schemes have beendevised, and as none of them to date have been generally adopted, forshaping the rear end of a projectile to reduce loss of kinetic energy,it is evident the shot as a whole was not symmetrical, or the scheme ofconstruction not practical, or could not perform the function. As ameans of illustration, if the cap on applicants projectile be removed itwould affect the accuracy of the shot and reduce the range and strikingvelocity, or if a blunt or square cap be employed the shot would tumble,due to the pressure energy applied at the base and the high resistanceat the nose or ogive of the projectile. If vthe angle is too abrupt,little or no energy is conserved at high velocity, for the rate of flowand expansion of a normal atmosphere at the base of a projectile having'a velocity of 2,184 ft. seconds is limited to that velocity. If thecylinder length of the shot is too long, skin friction destroys itsrotary velocity and, therefore, its accuracy at long range and anincreased tendency to tumble. A reduction of the cylinder length doesnot necessarily reduce the sectional density of the shot, for weight isadded to the shot by both the cap and the tapered rear end. A reductionof the cylinder length of a projectile moves the center of mass nearerto the pivotal point of resistance and rotation and, therefore, a reduced rotary velocity will sustain the-shot in stable equilibrium inrelation toithe trajec'tory. As an illustration of the effect offriction, a 12" shot, cylinder length 20",

weight 870 pounds,'fired from a gun having a twist of 1 turn to 25calibers, and a muzis a sectional view of a projectile embodyingtheinvention. In this figurethe tapered reaniend; is integral with thecylinder of the shoti Fig. 2 isa partial sectional view of a projectileshowing the rear end of the cylinder of the shot equipped witha'removable ta cred base.

der of the shot which extends from the bourrelet 2 to the rotating band3, and but slightly'ex'ceeds in length the caliber of the ferring toFig. 1, 1 the cylinshoe. 4 indicates the ogive of the shot proper,struck from a center on a line perpendicular to the axis of the shot andabout 2.6 calibers radius.

5 indicates a uniform tapered rear end diverging from a line of thecylinder at an angle of 11 18 and terminating with a base perpendicularto the axis of the shot and equipped with a base plug, fuse plug andvent plate 6 of any usual or preferred style, it being understood thebase plug opening is sufiiciently large to admit a tool for boring outthe shot to desired dimension.

7 indicates a soft steel cap secured in the usual Way to the ogive ofthe shot. This cap is struck on a 7.5 caliber radius and is designed todisplace the air at 186% of the velocity of the fired projectile.

8 indicates a lubricant recess bored and reamed in the cap 7 tolubricate and ease the point of the shot.

Referring to Fig. 2, 5 indicates a thimble forming the base of the shothaving inwardly inclined walls extending from a recessed shoulderprovided with aleft hand thread 9 that engages a corresponding threadedshoulder at the rear end of the cylinder of the shot, the angle of theinclined walls being the same as shown in Fig. 1, but terminating in asquare base of less diameter. The base of thimble 5 is provided with avent 10 and is for the purpose of allowing the gases of combustion fromthe powder chamber to flow into chamber 11 of the thimble at the pointof maximum pressure,

thereby relieving the gun of from 3,000 to' 4,000 pounds pressure perinch, the vent being so designed that the gases will be redischarged inthe gun down to a pressure of 500 pounds in excess of the pressure inthe bore at the time the projectile leavesthe glllm. The drawing toscale indicates a 12" s ot.

That the retardation in velocity of a fired projectile, due to theresistance of the air, may be understood, I offer the following solutionof the several losses of a 12" shot constructed in accordance with myinvention: weight of shot, 870 pounds; cylinder length, 14"; ogive ofcap, 7.5 calibers radius; tapered base,-14 2' to 6 square base; muzzlevelocity, 2,700 ft. seconds elevation, 12 36'; time of flight, 33.8seconds; altitude, 4,593; range, 24,200v yards; remaining velocity,1,746 ft. seconds.

To detemne the skin frictiom-The cube of the average velocity (2700 plus1746 divided by 2 equals 2223 equals 10985463567" Xthe constant .0135the coefiicient for the -51906315.Xti1ne of flight 33.8 seconds equals1754433447. divided by the density 836 (2223, average velocityX.186%veloci of equals 148303758X displacement of the air due to the are 0 thvelocity .35 equals ogive equals 413.5 ft. seconds, this velocity squareequals 170982 divided by the constant 120500 equals 1.41 pounds pressureas the altitude equals 4593 the average pressure of the air over thetrajectory equals 13.08 pounds pressure plus 1.41 equals' 14.49 poundsabsolute or a density of 836) equals 2098604.6X8.526 ft. the superficialarea of the shot subjected to skin friction due to the motion oftranslation equals 17889023 ft. pounds loss due to skin friction. Lossdue to displacement of the air equal to the square of the velocit ofdisplacement 413.5 ft. secondsXweig t of air displaced 3877.4 pounds(113" area of cross-section X range in ft. 72600 divided by 144 equals56970 cubic feetXwei ht per cubic foot equals .06806 equals 38%74pounds) equals 6629656068 divided by twice acceleration 64.32 equals10307301 ft. pounds loss due to dis lacement.

088 due to the pressure of the atmospkere.-We will first determine theabsolute pressure at the base of the projectile over that area ofcross-section perpendicular to the axis of the projectile. A vacuumtakes place at this base at all velocities above 2184 seconds, and asthe coeflicient of reduction equals .196 the projectile travels as manyfeet in the path of its flight above this velocity as below. Therefore,the pressure will equal for the higher velocity 13.08 pounds per inch;for the lower velocity, 13. e., from 2184 ft. seconds to 1746 ft.seconds, the' remaining velocity, we have an average velocity of 1965ft. seconds. Therefore, the absolute pressure over this area forone-half the length of the trajectory equals the square of 1965Xtheatmospheric pressure 13.08 pounds divided by the square of 2184 equal to10.58854 pounds pressure. To this we add the pressure over the firsthalf of the trajectory, being 13.08,

determine this pressure to be i as much for the entire area of base of2.95857 pounds per inch.

To determine the absolute pressure over the area of cross-section of thebeveled portion the sine of the angle equals .2425X the average velocity2223 equals 539.0775 ft. seconds, the velocity flow and expansion of theair, 539.0775 squareX13.08 and vided by the square of 2184 equals .7969pounds pressure perinch, and for an average pressure over the entirebase of the projectile it will be .597675 pounds; to this we add thepressure due to-the square base 2.9.5857, making 3.556245 poundsXthearea of cross-section 113"Xthe range in feet equal 29174723 ft. pounds,the loss due to the pressure of the atmosphere.

Here it is desired to call attention to a the projectile, or

properly constructed base. It will be noted the pressure resistance dueto the beveled portion is but .7969 pounds per inch, and for a squarebase at velocity considered it equals 11.83427 pounds per inch. We findthe sum of the total resistances equal 17889023 skin friction plus10307301 displacement plus 29174723 pressure loss equals 57371047 ft.pounds; muzzle energy equals 98610071 ft. pounds; energy in remainingvelocity equals 41234591 ft. pounds. Loss, 57375480 'ft. pounds.

In considering this invention it is to be understood velocities rangingfrom 3,000 ft.

seconds to 1,300 ft. seconds are considered as applicable to the schemeof construction herein given.

It is to be understood the removable tapered base may be constructedwithout a perpendicular or end wall without depart ing from the spiritof this invention.

What I claim as new and desire to se- 7 cure by Letters Patent is:

1. A hollow projectile provided with a cap, a cylindrical portion, and adetachable hollow base whose walls are substantially of the samethickness as the main projectile walls, and having an inwardly inclinedwall terminatin in a reduced diameter at right angles to e axis of theprojectile and having a reduced unobstructed opening through its rearwall communicating with the free interior air space of said base.

2. A hollow projectile provided with a cap that has an ogive greaterthan the ogive of the shot upon WlllCll it is mounted, a cylindricalportion that but slightly exceeds in length the caliber of theprojectile, and a beveled base.

3. A hollow projectile provided with a cap the ogive of which is struckon at least 6 caliber radius, a cylindrical portion of less diameterthan the bourrelet that but slightly exceeds in length the caliber ofthe projectile, and a beveled base terminating in a reduced diameter.

4. A hollow projectile provided with a sharp pointed cap having acentral longitudinal recess of uniform diameter on its inner face tointersect with the hardened point of the shot upon which the cap ismounted, a cylindrical portion that but slightly exceeds in length thecaliber of the projectile and less diameter than the bourrelet, and abeveled base.

In testimony whereof I afiix my signature.

Witness:

M. E. Cownm.

